Granzyme B is a pro-apoptotic serine protease found in the granules of cytotoxic lymphocytes (CTL) and natural killer (NK) cells. Granzyme B is released towards target cells, along with the pore-forming protein, perforin, resulting in its perforin-dependent internalization into the cytoplasm and subsequent induction of apoptosis (see, for e.g., Medema et al., Eur. J. Immunol. 27:3492-3498, 1997). However, during aging, inflammation and chronic disease, Granzyme B can also be expressed and secreted by other types of immune (e.g., mast cell, macrophage, neutrophil, and dendritic cells) or non-immune (keratinocyte, chondrocyte) cells and has been shown to possess extracellular matrix remodeling activity (Choy et al., Arterioscler. Thromb. Vasc. Biol. 24(12):2245-2250, 2004 and Buzza et al., J. Biol. Chem. 280:23549-23558, 2005).
Inhibitors of Granzyme B in humans have been limited to (a) relatively weak, nonspecific inhibitors such as isocoumarins (Odake et al., (1991), Biochemistry, 30(8), 2217-2227); (b) biological inhibitors such as serpinB9 (Sun et al., (1996), 1 Biol. Chem., 271(44), 27802-27809); (c) covalently coupled inhibitors such as aldehydes (Willoughby et al., (2002), Bioorg. Med. Chem. Lett., 12(16), 2197), halomethyl ketones (Kam et al., (2000), Biochim. Biophy. Acta, 1477(1-2), 307-323), and phosphonates (Mahrus and Craik, (2005), Chem. & Biol., 12, 567-77 and Kam et al., (2000)); and (d) tricyclic inhibitors (Willoughby et al., (2002)).
Nonspecific inhibitors (such as isocoumarins) are not sufficiently potent or specific to be effective treatments for Granzyme-B-related diseases, disorders, and conditions. Likewise, the use of biological inhibitors such as serpins is limited by the ability to deliver the inhibitor to the target mammal, the cost of manufacturing the biological agents, and other, off-target activities, such as inhibition of other serine proteases such as human neutrophil elastase (Dahlen et al., (1999), Biochim. Biophys. Acta, 1451(2-3), 233-41), Caspase-1 (Annaud et al., (1999), Biochem. J., September 15; 342 Pt3, 655-65; Krieg et al., (2001), Mol. Endocrinol., 15(11), 1971-82; and Young et al., (2000), J. Exp. Med., 191(9), 1535-1544); Caspase-4 and Caspase-8 (Annaud et al., (1999)).
The tricyclic inhibitors (Willoughby et al. (2001)) also suffer from synthetic complexity/high manufacturing cost due to the complex core and accompanying low water solubility.
Despite the advances in development of Granzyme B inhibitors, there exists a need for compounds that inhibit Granzyme B with selectivity, that are relatively simple to manufacture at low cost, and that do not present drug delivery challenges. The present invention seeks to fulfill this need and provides further related advantages.